Chronic Active Epstein-Barr Virus Disease Originates from Infected Hematopoietic Stem Cells

• EBV infects lymphoid, myeloid, and stem cells in CAEBV patients, so that HSCT is currently the only curative treatment for CAEBV disease.

• EBV-infected HSCs have a higher rate of differentiation, which speeds up the cellular infection and alters immune response in CAEBV.

Chronic active Epstein-Barr Virus (EBV) disease (CAEBV) is lethal syndrome due to persistent EBV infection. When diagnosed as CAEBV, EBV infection was observed in multiple hematopoietic lineages, but the etiology of CAEBV is still elusive. Bone marrow and peripheral cells derived from five CAEBV patients, one EBV-associated hemophagocytic lymphohistiocytosis (EBV-HLH) patient, and two healthy controls were analyzed. Multiple assays were applied to identify and characterize EBV-infected cells, including quantitative PCR (qPCR), PrimeFlow and single-cell RNA-sequencing (scRNA-seq). Based on scRNA-seq data, alterations in gene expression of particular cell types were analyzed between CAEBV patients and controls, and between infected and uninfected cells. One CAEBV patient was treated with allogeneic hematopoietic stem cell transplantation (HSCT), and the samples derived from this patient were analyzed again six month after HSCT. EBV infected the full spectrum of the hematopoietic system including both lymphoid and myeloid lineages, so as hematopoietic stem cells (HSCs) in the CAEBV patients. EBV-infected HSCs exhibited a higher differentiation rate towards downstream lineages, and the EBV infection had an impact on both the innate and adaptive immunity, resulting in inflammatory symptoms. EBV infected cells were thoroughly removed from the hematopoietic system after HSCT. Taken together, multiple lines of evidence presented in this study suggest that CAEBV disease originates from the infected hematopoietic stem cells, which might potentially lead to innovative therapy strategies for CAEBV.